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US 5,442,696 AGranted
Method and apparatus for detecting control signals
AssigneeAT&T Corp.
InventorsCraig R. Lindberg, David J. Thomson
Life of this patent
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AssigneeAT&T Corp.
InventorsCraig R. Lindberg, David J. Thomson
Estimating the term…
The present invention provides a method and apparatus for detecting control signal information for an element of a communication system. The control signal information is included in one or more segments of a signal communicated over a communication system channel. The invention provides for the application of a plurality of tapers to a segment of a communicated signal; the transformation of a tapered segment; the determination of a similarity score based on a transform of a tapered segment and a model of a control signal; the identification of control signal information based on a similarity score; and the creation of an indicator signal representative of the identified control signal information to the communication system element. The control signal information may comprise a dual-tone multi-frequency signal. The tapers may comprise a discrete prolate spheroidal sequence. A similarity score may be determined based on a ratio of energy distributions. The numerator of the ratio may comprise an energy distribution based on a control signal model, and the denominator of the ratio may comprise an energy distribution based on a difference between a transformed tapered segment and the control signal model.
A method of discriminating control signal information from non-control signal information, the control signal information for use by a communication system element, the control signal information and the non-control signal information included in one or more segments of a signal communicated over a communication system channel, the control signal information comprising signal components at one or more predetermined control signal frequencies, the non-control signal information comprising signal components at one or more information signal frequencies, the method comprising the steps of:
An apparatus for discriminating control signal information from non-control signal information, the control signal information for use by a communication system element, the control signal information and the non-control signal information included in one or more segments of a signal communicated over a communication system channel, the control signal information comprising signal components at one or more predetermined control signal frequencies, the non-control signal information comprising signal components at one or more information signal frequencies, the apparatus comprising:
Dependencies are inferred from the claim text.